| 摘要 |
PURPOSE:To obtain sufficient output torque by detecting a current flowed to a motor, providing means for integrating it, and raising a drive voltage as the integrating means increases, thereby reducing the drive voltage at a light load time, and increasing the drive voltage when a load increases. CONSTITUTION:A bus current detector 30 for detecting a current flowed to a motor 4 through an inverter 3 and an integrator 31 for integrating the output of the detector 30 are provided, and a chopper controller 12 raises the drive voltage as the output of the integrator 31 rises. Thus, when a load increases even at low frequency drive time, the drive voltage of the motor 4 can be increased to obtain sufficient drive torque. |
